This is by no means an exhaustive list, or a complete list, but here is a selection of local beer-centric places with winter and holiday beer selections for your drinking pleasure.
Rustico has, among others, the:
Harpoon Winter Warmer (Spiced w/ Cinnamon and Nutmeg)
Heavy Seas Winter Storm (Maryland-Extra Special Bitter)
Sierra Nevada Harvest Ale (Wet-Hopped American Pale Ale)
Southern Tier Old Man Winter Ale (New York-Old Ale)
Brickskeller/RFD list these, among others:
GEORGE GALE Christmas Ale 2001
HARVEY’S Christmas Ale 2000AD
FANTOME Winter Saison
FANTOME de Noel 2001
RIDGEWAY Lump of Coal Dark Holiday Stout
RIDGEWAY Santa’s Butt Winter Porter
RIVER HORSE Belgian Frostbite Winter Ale
Dogfish Head Alehouse (in Falls Church and Gaithersburg) has the Chicory Stout, a rich, dark beer made with a touch of roasted chicory, organic Mexican coffee, St. John’s Wort, and licorice root. Lost Dog Cafe in Arlington has the Anderson Winter Solstice, may have more. A little bird tells me that The Quarry House in Silver Spring will likely have some holiday beers around, as well.